1. Field of Invention
The present invention relates to methods and apparatuses for directing ultrasonic energy and more particularly to methods and apparatuses for directing ultrasonic energy for treating a fluid mixture contained in a vessel.
2. Background of the Invention
There are a number of conventional treatment processes for fluid mixtures including fluids including waste water and aqueous mixtures including waste matter. Treatment processes may include filtering, such as reverse osmosis filtering that removes solid contaminants from the waste water or aqueous mixture. However, because of environmental concerns, it may be difficult to dispose of the solid contaminants removed by filters. Furthermore, the filters themselves must be periodically back-flushed, which may be a time consuming process.
In an alternate process, microorganisms are disposed in the waste matter to consume or alter harmful elements in the waste matter. However, such systems generally process the waste matter in a batch mode and accordingly may be slow and labor intensive to operate.
Another conventional approach is to sterilize waste matter streams with ultraviolet light. One problem with this approach is that the waste matter must be positioned very close to the light source, which may make ultraviolet systems slow, expensive and inefficient.
Still another method includes exposing the waste matter stream to ozone which may alter harmful elements in the waste matter stream. One problem with this approach is that the cost of generating effective quantities of ozone historically has been relatively high that the process may not be economically feasible.
Another approach has been to dispose a fluid mixture containing a waste matter in a vessel and apply ultrasonic energy to the waste matter in a batch process. Exposing a fluid mixture comprising a fluid mixture to ultrasonic energy may cause chemical and/or physical changes to occur in the fluid mixture. For instance, cavitation of a liquid portion of the fluid mixture and generation of heat. Cavitation bubbles formed in the waste matter stream may grow in a cyclic fashion and ultimately collapse. This process creates very high temperatures, pressures, and thermal cycling rates. For example, it is estimated that this process may develop temperatures in the waste matter stream of up to 5,000 degrees Celsius, pressures of up to 1,000 atmospheres, and heating and cooling rates above 10 billion degrees Celsius per second for durations of less than one microsecond.
Apply ultrasonic energy to the waste matter in a batch process suffers from several drawbacks. Batch processing may be relatively slow and the efficiency with which ultrasonic energy is transmitted to waste matter contained in batch may be so low as to leave an unacceptable level of contaminants in the waste matter stream.
The present invention is directed toward methods and apparatuses for directing ultrasonic energy for treating a fluid mixture contained in a vessel with the directed ultrasonic energy.
In one embodiment of the invention, an apparatus for directing ultrasonic energy includes an ultrasonic energy emitter engaged with a support member. The emitter includes a first surface and a second surface facing opposite the first surface. A signal reverser is positioned adjacent to the second surface of the ultrasonic energy emitter. The signal reverser is biased against but not adhered to the ultrasonic energy emitter. The signal reverser is positioned to receive a portion of ultrasonic energy emitted from the emitter and direct at least part of the portion of ultrasonic energy back towards the emitter.
In one embodiment of the invention, an apparatus for a vessel having a first end, a second end opposite the first end, a vessel axis extending between the first and second ends, and a generally straight portion between the first and second ends. The vessel is configured to contain a fluid mixture. The vessel also includes an ultrasonic energy emitter positioned toward the first end of the vessel to direct ultrasonic energy into the fluid mixture during operation.
The apparatus may also include an ultrasonic energy focuser positioned toward the first end of the vessel at least proximate to the ultrasonic energy emitter. The focuser may have a focusing surface configured to focus the ultrasonic energy toward the vessel axis as the ultrasonic energy moves toward the second end of the vessel. The focusing surface may include a first portion having a first parabolic shape with a first curvature, and a second portion having a second parabolic shape with a second curvature different than the first curvature.
In another aspect of the invention, the apparatus may include an ultrasonic reflector positioned toward the second end of the vessel. The reflector may have a shaped, reflective surface positioned to reflect the ultrasonic energy toward the first end of the vessel. The reflective surface may be curved with an edge at least approximately tangent to a sidewall of the vessel and a tip on, and at least approximately tangent to, an axis spaced apart from the vessel sidewall and extending between the first and second ends of the vessel.
In still a further aspect of the invention, the ultrasonic energy emitter may include a first surface facing toward an interior of the vessel and a second surface facing opposite the first surface. The apparatus may further include a signal reverser positioned adjacent to the second surface of the ultrasonic energy emitter. The signal reverser may be biased against, but not adhered to, the ultrasonic energy emitter. The signal reverser is positioned to receive a portion of ultrasonic energy emitted from the emitter and reflect at least part of the portion of ultrasonic energy into the fluid mixture during operation.
In yet a further aspect of the invention, the signal reverser may have a third surface adjacent to the second surface of the emitter, a fourth surface opposite the third surface, and a dimension between the third and fourth surfaces of approximately one quarter the wavelength of ultrasonic energy passing into the signal reverser.
The invention is also directed toward a method for focusing ultrasonic energy in a fluid mixture. The method includes transmitting ultrasonic energy from an ultrasonic energy emitter into the fluid mixture, impinging the ultrasonic energy on a shaped focusing surface to converge the ultrasonic energy toward a focal point spaced apart from the ultrasonic energy emitter, and exposing a selected constituent of the fluid mixture to the ultrasonic energy as it converges toward the focal point. In another aspect of the invention, the method may be directed toward a method for reflecting ultrasonic energy in a volume of fluid mixture. Accordingly, the method may include transmitting the ultrasonic energy from the ultrasonic energy emitter through the volume of fluid mixture, and impinging the ultrasonic energy on a shaped reflecting surface spaced apart from the ultrasonic emitter to reflect ultrasonic energy back toward the ultrasonic energy emitter. The method may further include exposing a selected constituent of the fluid mixture to the ultrasonic energy as it passes from the ultrasonic energy emitter to the reflecting surface and from the reflecting surface back toward the ultrasonic energy emitter.
Exposing a fluid mixture comprising a fluid mixture to ultrasonic energy may cause chemical and/or physical changes to occur in the fluid mixture. Temperatures and pressures developed by the collapsing cavitation bubbles may have several advantageous effects on the constituents of the waste matter stream. For example, the collapsing bubbles may form radicals, such as OH radicals which are unstable and may chemically interact with adjacent constituents in the waste matter stream to change the chemical composition of the adjacent constituents. In one such process, an OH radical reacts with nitrates in the waste matter stream to produce gases such as nitrogen dioxide. The following are sample steps in such a reaction:
xe2x80x83NO3xe2x88x92+.OH_.NO3+OHxe2x88x92xe2x80x83xe2x80x83[1]
.NO3xe2x88x92+.OH_H2O.+.NO2xe2x80x83xe2x80x83[2]
.NO2+.NO2xe2x80x94.NO+.NO3xe2x80x83xe2x80x83[3]
.NO2+.NO2xe2x80x94.NO+.NO+O2xe2x80x83xe2x80x83[4]
.NO2+.H_.NO+.OHxe2x80x83xe2x80x83[5]
.NO2+.OH_.NO+O2.xe2x80x83xe2x80x83[6]
.NO2+.O._.NO2+O2xe2x80x83xe2x80x83[7]
In another embodiment, the reaction may continue, for example, in the presence of additional constituents to produce nitrites. In yet another embodiment, the cavitating bubble may alter trichloroethylene, for example, in accordance with the following simplified reaction:
(Cl)2Cxe2x95x90CHCl+2H2O_ . . . _Cl2+HCl+2H2+2COxe2x80x83xe2x80x83[1]
In other embodiments, the collapsing cavitation bubbles may have effects on other molecules that change a chemical composition of the molecules and/or change a phase of the molecules from a liquid or solid phase to a gaseous phase.
In still further embodiments, the collapsing cavitation bubbles may have effects on other constituents of the waste matter stream. For example, the combination of increased pressure and cavitation bubbles may disrupt a molecular structure of an organism and accordingly kill pathogenic organisms, such as bacteria. Temperatures and pressures observed in the presence of collapsing cavitation bubbles may serve to alter the structure of living cells and combust or oxidize constituents of the waste matter stream. For example, the high temperature produced by the collapsing cavitation bubble may oxidize constituents of the waste matter stream, producing by-products such as carbon dioxide and ash. The carbon dioxide may evolve from the waste matter stream and the ash may be filtered from the waste matter stream, as will be described in greater detail below. In still another embodiment, the collapsing cavitation bubbles may also separate constituents of the waste matter stream. For example, when the waste matter stream includes a mixture of oil, water, and an emulsifier, the collapsing cavitation bubbles may alter the molecular characteristics of the emulsifier and cause the emulsifier to lose its effectiveness.
Accordingly, oil and water may separate from each other and one or the other may be removed from the stream. Collapsing cavitation bubbles may have other effects on the waste matter stream that alter the characteristics of the constituents of the stream in a manner that makes the constituents more benign and/or allows the constituents to be more easily removed from the waste matter stream. In an alternate aspect of the invention, a chemical composition including a selected constituent may be oxidized to produce an ash and a gas. The fluid mixture may be contained under pressure while it is exposed to ultrasonic energy. The treatment vessel may be pneumatically coupled to a vacuum source after being exposed to the ultrasonic energy to remove gas from the fluid mixture. In still a further aspect of the invention, the fluid mixture may be exposed to a first ultrasonic energy having a first energy and a first frequency and the fluid mixture may be exposed to a second ultrasonic energy having a second energy and a second frequency.